[PATCH] riscv: boot: add zstd support

[Jisheng Zhang]

Support build the zstd compressed Image.zst. Similar as other
compressed formats, the Image.zst is not self-decompressing and
the bootloader still needs to handle decompression before
launching the kernel image.

Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
---
 arch/riscv/boot/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/boot/Makefile b/arch/riscv/boot/Makefile
index d1a49adcb1d7..c72de7232abb 100644
--- a/arch/riscv/boot/Makefile
+++ b/arch/riscv/boot/Makefile
@@ -56,6 +56,9 @@ $(obj)/Image.lzma: $(obj)/Image FORCE
 $(obj)/Image.lzo: $(obj)/Image FORCE
 	$(call if_changed,lzo)
 
+$(obj)/Image.zst: $(obj)/Image FORCE
+	$(call if_changed,zstd)
+
 $(obj)/loader.bin: $(obj)/loader FORCE
 	$(call if_changed,objcopy)
 
-- 
2.37.2